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CHAPTER II. 



THE MECHANICAL FUNCTIONS IN ZOOPHYTES. 



1 . General Observations. 



THE mechanism of an organized being is 

 designed to fulfil various important objects. 

 These we may distinguish into two classes ; the 

 one having reference to its internal welfare, the 

 other to its relations with external bodies. The 

 different parts of its system must, in the first 

 place, be mechanically united and supported, as 

 well as protected from injurious external impres- 

 sions ; and they must at the same time be so 

 constructed as to admit of all the internal move- 

 ments, which the performance of their functions 

 renders necessary. They must, in the second 

 place, be made capable of exerting upon exter- 

 nal matter the actions which conduce to their 

 well being ; and in order to enlarge their sphere 

 of action, they must have the power of transfer- 

 ring the whole body from one place to another ; 

 or, in other words, of effecting its progressive 

 motion. 



The objects included in the first of these 



